Novel dibenzothiophene chromophores with peripheral barbituric acceptors

Article abstract of DOI:10.1016/j.tet.2019.07.017

A series of novel chromophores based on central 2,8-disubstituted dibenzothiophene (DBT) or dibenzothiophene-S,S-dioxide (DBTO) has been designed and prepared. The interconnection of DBT(O) central scaffold with two peripheral barbituric acceptors via various π-spacer allowed significant property tuning of target chromophores. Four new final chromophores and six DBT(O)-intermediates have been successfully synthesized and fully characterized. Experimental and calculated data showed that the fundamental properties are affected by the chromophore A-π-D-π-A or A-π-A-π-A arrangement (DBT vs. DBTO) and the π-linker (ethenylene vs. ethynylene). Thorough structure-property relationships have been elucidated and discussed in detail.

Full text of DOI:10.1016/j.tet.2019.07.017

Accepted Manuscript
Novel dibenzothiophene chromophores with peripheral barbituric acceptors
Michaela Sperátová, Jaroslaw Jedyrka, Oldřich Pytela, Iwan V. Kityk, Ali H. Reshak,
Filip Bureš, Milan Klikar
PII:
S0040-4020(19)30759-8
https://doi.org/10.1016/j.tet.2019.07.017
TET 30459
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 24 May 2019
Revised Date: 27 June 2019
Accepted Date: 10 July 2019
Please cite this article as: Sperátová M, Jedyrka J, Pytela Oldř, Kityk IV, Reshak AH, Bureš F, Klikar M,
Novel dibenzothiophene chromophores with peripheral barbituric acceptors, Tetrahedron (2019), doi:
https://doi.org/10.1016/j.tet.2019.07.017.
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Novel dibenzothiophene chromophores with
peripheral barbituric acceptors
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Michaela Sperátováa, Jaroslaw Jedyrkab, Oldřich Pytelaa, Iwan V. Kitykb, Ali H. Reshakc,d, Filip Bureša, and
Milan Klikara,
aInstitute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice,
Studentská 573, Pardubice, 53210, Czech Republic.
bFaculty of Electrical Engineering, Institute of Electronic Systems, Czestochowa University of Technology,
Armii Krajowej 17, Czestochowa, 42-201, Poland.
c Nanotechnology and Catalysis Research Center (NANOCAT), University of Malaya, Kuala Lumpur 50603,
Malaysia
d Iraq University College (IUC), Al-Estiqlal St., Basrah – Iraq
A- -A- -A
A- -D- -A
switch-off
ICT
O O
S
S
Bu
Bu
Bu
Bu
O
O
O
O
N
N
N
N
sulfur
oxidation
O
O
O
O
N
N
N
N
Bu
Bu
Bu
Bu
O
O
O
O
structure-property
relationships

1
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Tetrahedron
journal homepage: www.elsevier.com
Novel dibenzothiophene chromophores with peripheral barbituric acceptors
Michaela Sperátováa, Jaroslaw Jedyrkab, Oldřich Pytelaa, Iwan V. Kitykb, Ali H. Reshakc,d, Filip Bureša,
and Milan Klikara,
aInstitute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, 53210, Czech Republic.
bFaculty of Electrical Engineering, Institute of Electronic Systems, Czestochowa University of Technology, Armii Krajowej 17, Czestochowa, 42-201, Poland.
c Nanotechnology and Catalysis Research Center (NANOCAT), University of Malaya, Kuala Lumpur 50603, Malaysia
d Iraq University College (IUC), Al-Estiqlal St., Basrah – Iraq
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A series of novel chromophores based on central 2,8-disubstituted dibenzothiophene (DBT) or
dibenzothiophene-S,S-dioxide (DBTO) has been designed and prepared. The interconnection of
DBT(O) central scaffold with two peripheral barbituric acceptors via various π-spacer allowed
significant property tuning of target chromophores. Four new final chromophores and six
DBT(O)-intermediates have been successfully synthesized and fully characterized. Experimental
and calculated data showed that the fundamental properties are affected by the chromophore
A-π-D-π-A or A-π-A-π-A arrangement (DBT vs. DBTO) and the π-linker (ethenylene vs.
ethynylene). Thorough structure-property relationships have been elucidated and discussed in
detail.
Available online
Keywords:
Dibenzo[b,d]thiophene
N,N´-dibutylbarbituric acid
Chromophore
π-Conjugated system
Knoevenagel condensation
2009 Elsevier Ltd. All rights reserved
.
1. Introduction
introducing D, A or π moieties. DBT(O) core is very often
decorated by polycyclic aromatics such as fluorene,[12]
fluoranthene,[13] anthracene,[14] etc. These extended π-systems
guarantee remarkable fluoresce. Emissive properties were also
Organic π-conjugated systems equipped with electron
donating and withdrawing substituents, so-called push-pull D-π-
A chromophores, found manifold applications in the field of
material chemistry.[1–5] Among ordinary electron donors
featuring positive mesomeric effect such as NR2 or OR groups,
thiophene occupies a prominent position due to its donating
power, planarity, and high polarizability.[6] Thiophene can also
be fused with another (hetero)aromatic rings to improve and
modify its electronic properties. Thieno[3,2-b]thiophene (TT)[7]
or dibenzo[b,d]thiophene (DBT)[8] are two typical
representatives. DBT is a popular central building block used for
the construction of various π-conjugated molecules, which found
application in modern optoelectronics. The popularity of the
DBT is not only due to its electronic features but also its facile
and selective halogenation and further modification via cross-
coupling reactions. For instance, bromination of the DBT using
Br2 is selective to the positions 2 and 8.[9] Moreover, the sulfur
atom undergoes easy oxidation by H2O2 to DBT-S,S-dioxide
(DBTO), [10] which leads to a singular switching of the
electronic properties (donor→acceptor). Subsequent bromination
of DBTO provides 3,7-disubstituted derivative which completes
the portfolio of easily accessible DBT(O) isomeric
chromophores.[11] Based on these parent DBT(O) scaffolds,
encountered
for
D-π-DBT(O)-π-D
systems
with
triphenylamine,[15–17] acridine,[18] carbazole,[19–21] or
thiophene[22] peripheral donors. Opposite arrangement with
peripheral acceptors (A-π-DBT(O)-π-A) is scarce, utilizing
mostly azines such as pyridine[23–26] or triazine[27]. The
DBT(O) may also be interconnected via various π-spacers to
oligomeric chain.[28] Based on the observed nonlinear and
fluorescent properties of DBT(O)-derived push-pull molecules,
they were used as two photon absorbing (2PA) materials for
bioimaging and tested as active materials in OLED and OFET
devices. Asymmetric DBT(O)-chromophores, e.g. those bearing
peripheral triphenylamine donor and cyanoacrylic acceptor, were
studied as sensitizers in DSSC.[29]
Despite a relatively large number of DBT(O) derivatives
synthesized to date, it is quite surprising that DBT(O) has not
been decorated by malonic acceptors so far. We have recently
systematically explored malonic acid and their derivatives as
electron withdrawing moieties focusing on their electronic
features.[30–32] (Thio)barbituric acid has been identified as
powerful acceptor with improved solubility due to possible
N,N’-disubstitution. Hence, we focus our attention towards a
series of chromophores 7–9 based on central DBT(O) unit and
mostly
———symmetrical
chromophores were assembled upon
Corresponding author. Tel.: +420-466-037-161; e-mail: milan.klikar@upce.cz; website: http://bures.upce.cz/klikar.html

2
Tetrahedron
ACCEPTED MANUSCRIPT
two peripheral barbituric acceptors connected via various π-
spacers (Figure 1). The target chromophores possess either
electron donating DBT unit (A-π-D-π-A systems; series a) or
electron withdrawing DBTO (A-π-A-π-A systems; series b). The
length of the π-linker has also been adjusted – none (7),
ethenylene (8) or ethynylene (9). The influence of the
aforementioned structure changes on fundamental properties of
7–9 has experimentally been investigated by differential scanning
calorimetry, cyclic voltammetry and electronic absorption
spectroscopy completed by DFT calculations and nonlinear
optical measurements. Based on the collected data, the structure-
property relationships have been elucidated.
6a−b were gained through a selective oxidation of alcohols 5a−b
using Dess-Martin reagent.[35] Despite a general excess of
reagents has been used, the intermediates 3–6 were always
partially contaminated by mono products, which were separated
by column chromatography. Due to their planar arrangement and
possible π-stacking, 3–6 are hardly soluble in common organic
solvents, which also hampered their easy purification. For
instance, aldehyde 4b is almost insoluble. Hence, the attained
yields mostly reflect purification issues rather than conversion of
the reactions. With all aldehydes in hand, the final twofold
Knoevenagel condensation with N,N´-dibutylbarbituric acid[31]
was catalyzed by Al2O3[36] providing target chromophores 7−9.
N,N´-Dibutylbarbituric acceptor ensured solubility of all target
molecules but it also prevent their easy crystallization. All final
molecules were purified by column chromatography. Whereas
extended chromophores 8a and 9a were isolated in satisfactory
yields of 71−78 %, DBTO-analogues 8b and 9b showed certain
instability during chromatography and, therefore, were gained in
lower yields. Finally, all attempts to isolate and purify
chromophores 7a−b, with the barbituric moiety appended
directly to the DBT(O), failed. The color change as well as TLC
and HR-MALDI-MS analyses of the crude reaction mixture
clearly confirmed presence of both 7a−b. However their isolation
as chemical individuals was not possible due to their reverse and
ready decomposition to starting aldehydes 3a−b and
N,N´-dibutylbarbituric acid. We have observed such behavior
already previously.[30]
Figure 1. General structural arrangements of target chromophores 7−9.
2. Results/Discussion
2.2. Thermal properties
2.1. Synthesis
Thermal characteristics of target chromophores 8−9 as well as
intermediates 3−6 were measured by differential scanning
calorimetry (DSC). The measured melting points (Tm) and
decomposition temperatures (Td) are given in the experimental
section. The DSC characteristics of target chromophores 8−9
were studied in detail with a scanning rate of 3 °C/min within the
range of 25 to 400 °C (Figure 2); the deduced Tm and Td values
are summarized in Table 1. Compounds 8a−b with ethenylene
π-linker exhibited sharp endothermic melting processes and
gradual decomposition during further heating. On the contrary,
a vigorous exothermic degradation without previous melting has
been observed for 9a−b with embedded triple bond. A
The synthesis of all target chromophores started from
commercially available dibenzothiophene 1 (Scheme 1). Upon its
bromination[9] and oxidation,[10] 2,8-dibromoDBT(O) 2a−b
were readily obtained. Twofold lithiation of dibromo derivatives
2a−b followed by formylation with DMF[33] afforded
dicarbaldehydes 3a−b. Intermediates 2a−b were also subjected to
a twofold Sonogashira cross-coupling reaction with propargyl
alcohol[30] providing DBT(O)-alcohols 5a−b. The π-system of
dicarbaldehydes 3a−b was further extended via Wittig reaction
with tributyl(1,3-dioxolan-2-ylmethyl)phosphonium bromide to
afford 4a−b exclusively as E-isomers.[34] Propargyl aldehydes
Scheme 1. Synthetic pathways leading to intermediate aldehydes 3, 4 and 6 (left) and final Knoevenagel condensation to target chromophores 8−9 (right).

3
monotropic solid-solid transition of metastable crystals (~175 °C)
followed by melting of stable form has been observed for 8a. As
can be seen from the gathered data, compounds 8a−b with
embedded double bond showed significantly higher thermal
robustness than ethynylene analogous 9a−b. The thermal
properties are also dictated by the DBT/DBTO central unit. The
DBTO with two additional oxygen atoms brings increased
thermal resistance as judged by both Tm and Td values. Despite
substituted with four butyl chains, 8b possesses the melting point
close to 250 °C. Compounds 9a−b decomposed 100 °C below Td
of 8a−b, their thermal behavior is clearly dictated by the presence
of thermally labile ethynylene π-linker.
were not determined due to their localization out of the
ACCEPTED MANUSCRIPT
AcCN/Bu4NPF6 potential window. The deduced Ep(ox1) and Ep(red1)
values were found within the range of 1.47 to 1.69 and −0.98 to
−0.75 V, respectively. Due to unavailability of half-wave
potentials, Ep(ox1) and Ep(red1) values were further recalculated to
the HOMO/LUMO levels (Table 1) and are clearly visualized in
energy level diagram (Figure 3).
E
LUMO steadily decreases when going from 8 to 9 (π-system
replacement) and from a to b (DBT→DBTO replacement).
Significantly increased EHOMO can be seen for A-π-D-π-A
molecules 8a and 9a with DBT central donor. Suggesting the
electrochemically determined HOMO levels similar to the
calculated ones (Figure 3), the opposite arrangement with central
DBTO acceptor (8b and 9b) brings deepened HOMO level and
enlarged ∆E. Hence, chromophores 8a and 9a with DBT central
donor showed the narrowest electrochemical gaps ∆E = 2.45/2.58
eV. The effect of ethenylene→ethynylene π-linker replacement is
less pronounced.
2.4. Optical absorption properties
Target chromophores 8−9 are yellow/orange solids, their
linear optical properties were examined by UV-Vis spectroscopy
in CH2Cl2. The literature shows, that DBT(O)-based molecules
generally exhibit extraordinary fluorescent behavior. However,
this is not the case of chromophores 8−9, which showed very
weak emission properties. We have observed previously that
interconnection of barbituric acceptor with a donor/π-system
quenches emission behavior.[30–32] The absorption spectra of
four target chromophores are shown in Figure 4; the longest-
wavelength absorption maxima λmax and the molar extinction
coefficients εmax are summarized in Table 1.
Figure 2. DSC curves of chromophores 8−9 within the range of 25−330 °C.
The longest-wavelength absorption maxima λmax range from
349 to 434 nm with εmax values of 45– 67×103 M-1·cm-1. The
spectra always exhibited one dominant band with an additional
shoulder. The shoulder is either shifted hypsochromically (for
A-π-D-π-A DBT-chromophores 8a and 9a) or bathochromically
(for A-π-A-π-A systems 8b and 9b). This splitting of the
absorption bands is due to a coupling between branches and
reflects quadrupolar arrangement of target chromophores. For
V-shaped chromophores, the Frenkel exciton model predicts
splitting of the singlet excited state into two bands positioned
symmetrically with respect to the band of the corresponding
linear D-π-A molecule.[37] As can be seen, the position of the
bands are mainly dictated by the central unit. An apparent ICT
from the central electron releasing DBT unit into two peripheral
barbituric acceptors shifts the spectra of 8a and 9a
bathochromically as compared to A-π-A-π-A systems 8b and 9b
with DBTO central acceptor (∆λmax ≈ 75 nm/0.6 eV). The
π-linker has less pronounced effect on the absorption spectra;
a small difference (∆λmax = 5−10 nm/≈0.05 eV) has been found
between chromophores 8 and 9 with ethenylene and ethynylene
linkers, respectively. Hence, the spectra of chromophores 9a−b
are significantly hypsochromically and hypochromically shifted.
In accordance with the electrochemical measurements, the most
bathochromically shifted CT-band and the lowest optical gap
have been measured for chromophore 8a.
Figure 3. Energy level diagram with electrochemical (black) and DFT
calculated (red) HOMO/LUMO energies of chromophores 7−9.
2.3. Electrochemistry
The electrochemical characterization of target chromophores
8−9 was carried out in acetonitrile containing 0.1 M Bu4NPF6 in
a three electrode cell by cyclic voltammetry (CV). The acquired
data are summarized in Table 1, CV diagrams are given in the
SM. The first oxidations and reductions were determined as
irreversible processes followed by subsequent oxidations within
positive potentials. Although consecutive or simultaneous
multiple-electron reductions can be assumed for chromophores
with quadrupolar character, further reductions were not observed
within the available negative potential window (Figure S6).
Based on judged peak currents ip(ox1/red1) for illustrative molecule
8a, the first oxidations and reductions were likely recorded as
one-electron processes; their potentials are clearly a function of
the chromophore structure. It is assumed that the first reduction
takes place at the barbituric acceptor. The first oxidation most
likely involves either thiophene central donor (DBT) or is spread
over entire π-conjugated system (DBTO). The peak potentials of
the first oxidation Ep(ox1) for DBTO-chromophores 8b, and 9b
Solvatochromism of chromophores 8−9 was further
investigated in nonpolar toluene and polar acetonitrile. The
recorded spectra are depicted in Figures S10-11 (see the SM) and
the corresponding longest-wavelength absorption maxima are
summarized in Table S1. As a general trend, all chromophores
8−9 showed slight hypsochromic shift with increasing the solvent
polarity (toluene→CH2Cl2→AcCN). It indicates that the ground
state of these molecules is slightly more polar compared to the
excited state regardless of their push-pull or pull-pull character.

4
Tetrahedron
ACCEPTED MANUSCRIPT
Table 1. Fundamental properties of target chromophores 8−9.
A
A
SHG
THG
Tm
Td
Ep(ox1) Ep(red1)
∆E
EHOMO ELUMO
λmax
εmax
Comp.
[pmV-1]f [a.u.]f
[°C]a [°C]b
[V]c
[V]c
[eV]c
[eV]d
[eV]d
[nm/eV]e
[103 M-1cm-1]e
8a
8b
9a
9b
210
247
-
260
270
160
160
1.47
–0.98
–0.82
–0.89
–0.75
2.45
–5.94
–3.49
–3.65
–3.58
–3.72
404, 434/3.07, 2.86
359, 388/3.45, 3.19
396, 427/3.13, 2.90
349, 383/3.55, 3.24
53.1, 56.2
66.8, 48.0
45.4, 49.4
2.89
1.56
2.83
1.21
41
8
-
1.69
-
-
2.58
-
-
–6.16
-
35
-
50.6, 32.9
6
aTm = melting point (the point of intersection of a baseline and a tangent of thermal effect = onset). Td = thermal decomposition (pyrolysis in N2 atmosphere).
cEp(ox1) and Ep(red1) are peak potentials of the first oxidation and reduction (irreversible processes), respectively, as measured by CV at scan rate 100 mVs-1; all
potentials are given vs. SSCE, ∆E = Ep(ox1) – Ep(red1). d−EHOMO/LUMO = Ep(ox1/red1) + 4.429 (in AcCN vs. SCE)[38] + 0.036 [difference between SCE (0.241 vs. SHE)
b
and SSCE (0.205 vs. SHE)].[39] Measured in CH2Cl2 at c ≈ 1×10-5 M. Second- and third-harmonic generations measured in oligoether acrylate at probing
e
f
wavelength 1064 nm.
The experimental SHG responses were maximal for the DBT-
derived dipolar chromophores 8a and 9a with A-π-D-π-A
architecture. On the contrary, DBTO-derived chromophores 8b
and 9b are less polarized with diminished SHG coefficients. The
SHG measurements have also identified that chromophores 8a–b
with ethenylene linker possess slightly larger NLO activity than
ethynylene analogues 9a–b (Table 1). Compared to laser
stimulated SHG efficiency of other organic chromophores
measured
at
similar
conditions,
e.g.
2-(pyrene-1-
yl)ethenylpyridine[41] or indolino-oxazolidine[42] derivatives,
V-shaped chromophores 8 and 9 have demonstrated slightly
better efficiency.
2,25
3+
BBOδ 5% Nd
2,00
1,75
1,50
1,25
1,00
0,75
0,50
0,25
0,00
9b
9a
8b
8a
Figure 4. UV-Vis absorption spectra of chromophores 8−9 measured in
CH2Cl2 at c ≈ 1×10-5 M.
2.5. Nonlinear optical properties
0
20
40
60
2
80
100
FUN [J/m ]
The nonlinear optical properties of chromophores 8–9 were
explored by laser stimulated SHG and THG measurements. The
powdered samples were embedded into the oligoether acrylate
photopolymer matrices and were aligned in the dc-electric field
using photo-solidification by a method similar to that we have
used previously.[40] 5% Nd3+BiB3O6 crystallites in powder form
were used as reference samples. Pulsed Nd:YAG laser emitting at
λ = 1064 nm with pulse duration of 8 ns and frequency repetition
of 10 Hz was applied as a principal laser source, see the SM for
detailed description of the experimental set-up. The principal
dependence of the SHG versus the fundamental energy density
for s-s polarization is shown in Figure 5.
The obtained SHG data are slightly disturbed by the photo-
thermal destruction and occurrence of laser stimulated
absorption. The fluorescence contribution was spectrally
separated by interference filters. Figure 5 clearly shows that the
highest experimental SHG efficiency was achieved for
chromophore 9a. The SHG nonlinear optical coefficients that
take into account renormalization due to absorption (both linear
and two-photon) as well as fluorescence are presented in Table 1.
Figure 5. Typical dependences of laser stimulated SHG of chromophores 8–9
vs. fundamental energy density.
The third-order susceptibilities have been determined by
maximal values of the THG versus the rotating angle and have
been referenced to powdered Y3Al5O12:Cr samples with known
NLO susceptibilities.[43] The photo-thermal effect did not
exceed 5 to 7 K. An interference filter at 355 nm with the spectral
width of about 10 nm with two additional interference filters at
345 and 365 nm, spectrally cutting the parasitic fluorescence
scattered background, were employed to separate the reflected
scattered signal from the NLO response. See the SM for more
detailed description of the THG set-up. The typical dependences
of the THG versus the fundamental 1064 nm nanosecond pulsed
beams are presented in Figure 6. The evaluated values of the
third-order susceptibilities vary within the range of 6−41 pm2/V2
(Table 1) and are comparable with the third-order optical
nonlinearities of 8-hydroxyquinoline nickel complexes measured
at similar condition.[44] Similar to SHG coefficients, the THG

5
responses of chromophores 8–9 are affected by the central
chromophores, especially molecules 8a and 9a possess
ACCEPTED MANUSCRIPT
DBT/DBTO unit (a vs. b) as well as the ethenylene/ethynylene
π-linkers (8 vs. 9). Whereas 8b and 9b showed diminished THG,
the largest third-order NLO responses were recorded for 8a and
9a.
energetically quasi-degenerated LUMO and LUMO+1 (Figure
S13).
The HOMO/LUMO localizations were calculated at
B3LYP/6-311++G(2df,p) level using DFT-optimized geometries
and visualized in OPchem.[48] The frontier molecular orbitals in
representative chromophores 9a and 9b are shown in Figure 7;
for complete listing see the SM. As expected, there is a clear
HOMO/LUMO separation in push-pull chromophores in series a
confirming their ICT character. Whereas the HOMO is centrally
localized on the DBT donor, the LUMO is shifted towards both
barbituric acceptors. The HOMO-1 and LUMO+1 are localized
similarly. On the contrary, there is no HOMO/LUMO separation
in A-π-A-π-A chromophores in series b. Both HOMO-1 and
LUMO+1 are spread over the π-linker adjacent to the barbituric
acceptors.
Using femtosecond laser at λ=1045 nm with pulse duration
180 fs gives a similar dependences which imply that the role of
the vibrational subsystem is not crucial here. The values of the
photo induced NLO are relaxed up to the initial magnitudes
within 1 to 2 min, which confirms a significant role of trapped
metastable levels situated within forbidden energy gap. This will
be a subject of a separate studies in a near future. However, the
recorded photo induced changes of the second-order
susceptibilities are higher than many other NLO-phores, e.g.
inorganic-organic hybrid nanocomposites[45] or 4-(5-nitro-1,3-
benzoxazol-2-yl)aniline derivatives.[46]
All target chromophores 7−9 possess C2v group of symmetry
with the ground state dipole moments µ between 2 and 5.5 D.
DBT-chromophores in series a showed higher dipolar character
than chromophores in series b. The calculated second-order
polarizabilities β range from 24 to 302×10-30 esu and showed
similar trends as the experimental SHG values. Push-pull DBT-
chromophores in series a possess approximately four times larger
β values in comparison to DBTO-analogues in series b. The β
values also increases with elongation of the π-linker (7→8/9).
However, almost identical hyperpolarizabilities were calculated
for both pairs of chromophores with ethenylene/ethynylene
π-linkers (8a/9a and 8b/9b). Hence, the largest NLO coefficients
β were calculated for chromophore 8a (302×10-30 esu) and 9a
(298×10-30 esu).
0,35
9a
0,30
0,25
0,20
0,15
0,10
0,05
0,00
8a
40
45
50
55
FUN [J/m ]
60
65
70
2
Figure 6. Dependence of THG for chromophores 8a and 9a vs. fundamental
energy density.
2.6. Theoretical DFT calculations
Spatial and electronic properties of target chromophores were
investigated using Gaussian®16W software[47] package at the
DFT level. Initial geometries of molecules 7−9 were optimized
by DFT B3LYP/6-311+G(2df,p) method. Energies of the frontier
molecular orbitals, their differences ∆E and ground state dipole
moments µ were calculated at DFT B3LYP/6-311++G(2df,p)
level in acetonitrile (AcCN). In order to accelerate the DFT
calculation, butyl substituents of the barbituric moieties were
replaced by methyls. The first hyperpolarizabilities β were
computed at DFT B3LYP/6-311++G(2df,p) level in vacuum at
1064 nm. Theoretical electronic absorption spectra were
calculated at TD-DFT (nstates = 8) B3LYP/6-311++G(2df,p)
level in CH2Cl2 and corresponding λmax values were deducted.
All calculated data are summarized in Table 2 and Table S2.
The calculated HOMO and LUMO energies range from −7.07
to −6.17 and −3.56 to −3.08 eV and showed clear dependence on
the structural arrangement of the particular chromophore as can
be seen from the energy level diagram in Figure 3. The LUMO
energies, HOMO–LUMO and optical gaps correlate very tightly
with the experimental data obtained by electrochemistry and
UV-Vis spectra (see Figures S14–S16 in the SM). The DFT
calculations have identified similar structural features affecting
fundamental properties of target chromophores; namely
replacement of the central unit (DBT→DBTO) and
presence/elongation of the π-linker. Hence, the widest and
narrowest gaps have been calculated for A-π-A-π-A DBTO-
chromophore 7b without extended π-linker (∆E = 3.61 eV) and
A-π-D-π-A DBT-chromophore 8a with embedded double bonds
(∆E = 2.99 eV). Based on the A-π-D-π-A character of DBT-
Figure 7. The HOMO (red) an LUMO (blue) localizations in representative
chromophores 9a and 9b.
Figure
8 shows representative overlapped spectra of
chromophore 8b; for complete listing see the SM. The calculated
DFT
λmax
values are listed in Table 2. Both experimental and
calculated optical gaps (1240/λmax) showed very tight correlation
as shown in Figure S16. Despite the TD-DFT spectra are slightly
red-shifted (∆λmax ≈ 40 nm/0.25 eV), both spectra are almost
identical with the same bands and shoulders. According to the
analysis of the particular oscillators, the main band of DBT
chromophores 7a, 8a and 9a consists of the HOMO→LUMO
transition. The hypsochromically shifted shoulders are originated
from the HOMO–1→LUMO and HOMO−1→LUMO+1
transitions. For DBTO analogues 7b, 8b and 9b is the situation
completely opposite. The main band is created by the HOMO–
1→LUMO and HOMO−1→LUMO+1 transitions, while the
bathochromcially shifted shoulder is generated by the
HOMO→LUMO transition with a weaker oscillator strength.

6
Tetrahedron
ACCEPTED MANUSCRIPT
Table 2. Principal DFT calculated characteristics of target chromophores 7–9.
DFT
∆E
µ
β
× 10-30
λmax
EHOMO ELUMO
Group of symmetry
Comp.
[eV]a
[eV]a
[eV]a [D]a
[esu]b
[nm/eV]c
7a
7b
8a
8b
9a
9b
−6.46
−7.07
−6.17
−6.70
−6.34
−6.94
−3.08
−3.46
−3.18
−3.46
−3.31
−3.56
3.38
3.61
2.99
3.24
3.03
3.38
3.95
4.43
5.37
3.37
5.56
1.98
85
24
425/2.92
399/3.11
478/2.59
434/2.86
472/2.63
420/2.95
C2v
C2v
C2v
C2v
C2v
C2v
302
73
298
71
b
aCalculated at the DFT B3LYP/6-311++G(2df,p) level in AcCN. Calculated at the DFT B3LYP/6-311++G(2df,p) level in vacuum at 1064 nm (−2ω;ω,ω).
cCalculated at the TD-SCF (nstates = 8) B3LYP/6-311++G(2df,p) level in CH2Cl2.
4. Experimental section
4.1. General methods
Compounds 2a−b and 3a are known molecules. The
preparation and characterization of dibromo derivatives 2a and
2b are given to the SM. The preparation of N,N´-
dibutylbarbituric acid is carried out according our earlier
procedure.[31] Starting DBT 1 as well as other reagents are
commercially available. All commercial chemicals, reagents and
solvents were purchased from suppliers such as Sigma Aldrich,
TCI, Acros at reagent grade and were used as obtained. The dry
THF was always freshly distilled from Na/K alloy and
benzophenone under an inert atmosphere of argon. Formylation
reaction, Wittig olefination and Sonogashira cross-coupling
reaction were carried out in flame-dried flasks under argon.
Column chromatography was carried out with silica gel 60
(particle size 0.040−0.063 mm, 230−400 mesh; Merck) and
commercially available solvents. Thin-layer chromatography
(TLC) was conducted on aluminum sheets coated with silica gel
60 F254, obtained from Merck, with visualization by a UV lamp
(254 or 360 nm). Melting points of 2a−b were determined by
using Büchi B-540 instrument in open capillaries. Thermal
properties of all remaining molecules were measured by
differential scanning calorimetry with a Mettler-Toledo STARe
System DSC 2/700 equipped with FRS 6 ceramic sensor and
cooling system HUBER TC100-MT RC 23. The measurements
were carried out in open aluminous crucibles under N2 inert
atmosphere. DSC curves were determined with a scanning rate of
3 °C/min within the range 25−400 °C for 8−9 and with a
scanning rate of 10 °C/min within the range 100−400 °C for 3−6.
Melting point and temperature of decomposition were
determined as intersection of baseline and tangent of peak (onset
Figure 8. The overlapped and fitted experimental (violet) and calculated
(black) spectra of chromophore 8b.
3. Conclusion
Dibenzothiophene- and dibenzothiophene-S,S-dioxide-derived
V-shaped chromophores with peripheral barbituric acceptors
were designed and synthesized in a straightforward manner. The
synthesis involved bromination and oxidation of commercially
available dibenzothiophene and its subsequent modification via
formylation, Wittig olefination, Sonogashira cross-coupling and
final Knoevenagel condensation. Target chromophores with
barbituric acceptors connected directly to DBT(O) central unit
proved unstable. The fundamental thermal and optoelectronic
properties were studied by DSC analysis and electrochemical and
absorption spectra. It has been demonstrated that the used central
donor (DBT) or acceptor (DBTO) as well as the
ethenylene/ethynylene π-linkers affect the properties of
chromophores 8 and 9 most significantly. The differences are
mostly due to A-π-D-π-A (DBT) or A-π-A-π-A (DBTO)
architecture of series a and b. These structural features also
dictates the NLO responses of both chromophore types, the latter
showed significantly diminished second- and third-order
susceptibilities. The experimental data is further supported by
DFT calculations. The lowest electrochemical/optical gaps and
largest SHG and THG responses were measured for
chromophores 8a and 9a based on the DBT central donor with
A-π-D-π-A arrangement and ethenylene/ethynylene π-linkers.
1
point). H and 13C NMR spectra were recorded at 400 and 100
MHz, respectively, with a Bruker AVANCE 400/500 instrument
or 500 and 125 MHz, respectively, with Bruker AscendTM 500 at
25 °C. Chemical shifts are reported in ppm relative to the signal
1
of Me4Si. The residual solvent signal in the H and 13C NMR
spectra was used as an internal reference (CDCl3 7.25 and 77.25
ppm; d6-DMSO 2.55 and 39.51 ppm). Apparent resonance
multiplicities are described as s (singlet), d (doublet), dd (doublet
of doublet), t (triplet) and m (multiplet); the coupling constants of
multiplets (3J or 4J) are given in Hz. Mass spectra were measured
with
a GC-MS configuration comprised of an Agilent
Technologies 6890N gas chromatograph equipped with a 5973
Network MS detector (EI 70 eV, mass range 33–550 Da). High
resolution MALDI MS spectra were measured on a MALDI mass
spectrometer LTQ Orbitrap XL (Thermo Fisher Scientific,

7
Bremen, Germany) equipped with nitrogen UV laser (337 nm,
4.4. General Method C (Sonogashira cross-coupling reaction)
ACCEPTED MANUSCRIPT
60 Hz). The LTQ Orbitrap instrument was operated in positive-
ion mode over a normal mass range (m/z 50-2000) with
resolution 100 000 at m/z = 400. The survey crystal positioning
system (survey CPS) was set for the random choice of shot
position by automatic crystal recognition. 2,5-Dihydroxybenzoic
acid (DHB) was used as a matrix. Mass spectra were averaged
over the whole MS record for all measured samples. The
absorption spectra were measured on a Hewlett-Packard 8453
spectrophotometer in CH2Cl2 at 2×10-5 M. The electrochemical
behavior of target chromophores were investigated by cyclic
voltammetry in acetonitrile containing 0.1 M Bu4NPF6 in a three
electrode cell by cyclic voltammetry (CV). The working
electrode was glassy carbon disk (1 mm in diameter). Leak-less
Ag/AgCl electrode (SSCE) containing filling electrolyte (3.4 M
KCl) and titanium rod with a thick coating of platinum were used
as the reference and auxiliary electrodes. All peak potentials are
given vs. SSCE. Voltammetric measurements were performed by
using an integrated potentiostat system ER466 (eDAQ Europe,
Warszawa, Poland) operated with EChem Electrochemistry
software.
The compounds 5a−b were synthesized via modified literature
procedure.[30] Brominated derivative 2a or 2b (3 mmol) and
propargyl alcohol (0.7 mL, 12 mmol) were dissolved in dried
solution of THF/Et3N (100:25 mL). Argon was bubbled through
the solution for 15 min, whereupon [PdCl2(PPh3)2] (105 mg,
0.15 mmol), PPh3 (39 mg, 0.15 mmol) and CuI (57 mg, 0.3
mmol) were added, and the reaction mixture was stirred under
argon at 60 °C for 24 hours. The solvents were evaporated and
the crude product was extracted portioned between NH4Cl (100
mL) and CH2Cl2 (3×100 mL). The combined organic extracts
were dried (Na2SO4) and the solvents were evaporated in vacuo.
The crude product 5a or 5b was purified by column
chromatography (SiO2, CH2Cl2/EtOAc 1:1) or precipitated from
CH2Cl2 solution with hexane.
4.5. General Method D (Dess-Martin Oxidation)
The compounds 6a−b were synthesized via modified literature
procedure.[35] Alcohol 5a or 5b (2 mmol) and Dess-Martin
periodinane (1.87 g, 4.4 mmol) were suspended in CH2Cl2
(200 mL). The reaction mixture was stirred at 25 °C for 24 hours,
diluted with water (100 mL) and extracted with CH2Cl2
(2×100 mL). The combined organic layers were dried (Na2SO4)
and the solvent was removed in vacuo. The crude product 6a or
6b was purified by column chromatography (SiO2,
CH2Cl2/EtOAc 25:1).
4.2. General Method A (formylation reaction)
The title compounds 3a−b was synthesized via modified
literature procedure.[33] Brominated derivative 2a or 2b
(10 mmol) was dissolved in dry THF (150 mL) and the solution
was cooled to −78 °C. Argon was bubbled through the solution
for 15 min and TMEDA (3.0 mL, 20 mmol) followed by n-BuLi
(13.75 mL 1.6 M in hexane, 22 mmol) were added dropwise. The
reaction mixture was stirred at −78 °C for 90 min. DMF (3.9 mL,
50 mmol) was added and the reaction mixture was stirred at room
temperature for 24 h. The reaction mixture was quenched with
saturated solution of KH2PO4 (150 mL) and extracted with
EtOAc (3×150 mL). The combined organic fractions were dried
(Na2SO4) and the solvents were removed in vacuo. The crude
product 3a or 3b was purified by column chromatography (SiO2,
CH2Cl2/EtOAc 25:1).
4.6. General Method E (Knoevenagel Condensation)
The final chromophores 8a−b or 9a−b were synthesized via
modified literature procedure.[36] Aldehyde 4a, 4b, 6a or 6b
(0.5 mmol) and N,N´-dibutylbarbituric acid (360 mg, 1.5 mmol)
were dissolved in CH2Cl2 (75 mL) and Al2O3 (510 mg, 5 mmol,
Brockmann II-III) was added. The reaction mixture was stirred at
25 °C for 24 hours. Al2O3 was filtered off and the filtrate was
evaporated in vacuo. The crude product was purified by column
chromatography (SiO2, CH2Cl2/EtOAc 50:1).
4.3. General Method B (Wittig olefination)
4.7. Dibenzo[b,d]thiophene-2,8-dicarbaldehyde (3a)
The compounds 4a−b were synthesized via modified literature
procedure.[34] Aldehyde 3a or 3b (2 mmol) and tributyl(1,3-
dioxolan-2-ylmethyl)phosphonium bromide (1.63 g, 4.4 mmol)
were dissolved in dry THF (50 mL). Argon was bubbled through
the solution for 15 min, NaH (144 mg, 6 mmol) was added and
the reaction mixture was stirred at room temperature for 24 h.
The reaction mixture was diluted with water (100 mL) and
extracted with EtOAc (3×100 mL). The combined organic layers
were dried (Na2SO4) and the solvents were evaporated in vacuo.
The residue was dissolved in THF (100 mL), 12% HCl (50 mL)
was added and the solution was stirred for 1 h. The reaction
mixture was diluted with water (100 mL) and extracted with
EtOAc (3×100 mL). Both products 4a and 4b are sparingly
soluble in common organic solvents. Therefore, the collected
organic suspensions was concentrated in vacuo and precipitate
was filtered off. The crude product 4a or 4b was suspended in
EtOAc (50 mL), the suspension was refluxed for 30 min, cooled
to 25 °C and the product was isolated by filtration. After drying,
products 4a and 4b were used in the following reaction step
without further purification. A full purification of small
quantities is possible by column chromatography (SiO2,
CH2Cl2/EtOAc 10:1) using large excess of the eluting solvents.
The title compound was prepared from bromo derivative 2a
(3.42 g) following the general procedure A. The product 3a was
obtained as a white solid (1.68 g, 70 %; Ref.[33] 75 %). Rf = 0.65
(CH2Cl2); Tm = 235 °C (Ref.[49] 233−234 °C), Td> 340 °C.
EI-MS (70 eV) m/z (rel. int.): 240 ([M]+, 100), 211 (41), 182
1
(25), 139 (30). H-NMR (500 MHz, 25 °C, d6-DMSO): δ = 8.10
(dd, J1 = 8 Hz, J2 = 1.5 Hz, 2H, CHAR), 8.36 (d, J = 8.5 Hz, 2H,
CHAR), 8.72 (s, 2H, CHAR), 9.10 (d, J = 1 Hz, 2H, CHAR),
10.21 ppm (s, 2H, CH=O). 13C-NMR (125 MHz, 25 °C, CDCl3):
δ = 123.82; 124.18; 127.87; 133.92; 135.58; 146.31; 191.66 ppm.
4.8. 5,5-Dioxo-5H-5λ6-dibenzo[b,d]thiophene-2,8-dicarbalde-
hyde (3b)
The title compound was prepared from bromo derivative 2b
(3.74 g) following the general procedure A. The product was
obtained as a yellowish solid (1.85 g, 68 %). Rf = 0.45 (CH2Cl2);
Tm = 320 °C, Td> 360 °C. EI-MS (70 eV) m/z (rel. int.): 272
1
([M]+, 100), 215 (73), 150 (42), 115 (35). H-NMR (500 MHz,
25 °C, d6-DMSO): δ = 8.26 (dd, J1 = 8 Hz, J2 = 1 Hz, 2H, CHAR),
8.35 (d, J = 8 Hz, 2H, CHAR), 8.92 (s, 2H, CHAR), 10.21 ppm (s,
2H, CH=O). 13C-NMR (125 MHz, 25 °C, d6-DMSO): δ = 123.17;
123.80; 131.04; 132.83; 140.83; 140.92; 192.05 ppm.

8
Tetrahedron
ACCEPTED MANUSCRIPT
4.9. (2E,2'E)-3,3'-(Dibenzo[b,d]thiene-2,8-diyl)di(prop-2-enal)
°C. 1H-NMR (500 MHz, 25 °C, d6-DMSO): δ = 7.89 (dd, J1 = 8.5
Hz, J2 = 1.5 Hz, 2H, CHAR), 8.31 (d, J = 8.5 Hz, 2H, CHAR), 9.04
(d, J = 1 Hz, 2H, CHAR), 9.55 ppm (s, 2H, CH=O). 13C-NMR
(100 MHz, 25 °C, CDCl3): δ = 89.10; 95.01; 116.31; 123.64;
127.16; 131.77; 134.98; 143.10; 176.84 ppm. HR-FT-MALDI-
MS (DHB) m/z: calculated for C18H9O2S+ ([M+H]+): 289.03178;
found 289.03193.
(4a)
The title compound was prepared from aldehyde 3a (480 mg)
following the general procedure B. The product 4a was obtained
as a yellowish solid (467 mg, 80 %). Rf = 0.50 (CH2Cl2/EtOAc
1
20:1); Tm = 260 °C, Td> 320 °C. H-NMR (500 MHz, 25 °C,
d6-DMSO): δ = 7.16 (dd, J1 = 16 Hz, J2 = 8 Hz, 2H, CH),
7.94−7.97 (m, 4H, CH+CHAR), 8.23 (d, J = 8.5 Hz, 2H, CHAR),
9.10 (d, J = 1 Hz, 2H, CHAR), 9.81 ppm (d, J = 8 Hz, 2H, CH=O).
13C-NMR (125 MHz, 25 °C, d6-DMSO): δ = 122.58; 124.33;
128.68; 129.01; 131.74; 135.85; 142.43; 153.46; 194.98 ppm.
HR-FT-MALDI-MS (DHB) m/z: calculated for C18H13O2S+
([M+H]+): 293.06308; found 293.06512.
4.14. 3,3'-(5,5-Dioxo-5H-5λ6-dibenzo[b,d]thiene-2,8-
diyl)di(prop-2-ynal) (6b)
The title compound was prepared from alcohol 5b (648 mg)
following the general procedure D. The product was obtained as
a light ocher solid (480 mg, 75 %). Rf = 0.60 (CH2Cl2); Td>
230 °C. 1H-NMR (400 MHz, 25 °C, d6-DMSO): δ = 8.04 (d,
J = 7.6 Hz, 2H, CHAR), 8.24 (d, J = 8 Hz, 2H, CHAR), 8.77 (s, 2H,
CHAR), 9.56 ppm (s, 2H, CH=O). 13C-NMR (125 MHz, 25 °C,
d6-DMSO): δ = 89.82; 90.28; 123.03; 125.00; 127.82; 130.65;
135.80; 138.45; 178.75 ppm. HR-FT-MALDI-MS (DHB) m/z:
calculated for C18H9O4S+ ([M+H]+): 321.02161; found
321.02234.
4.10. (2E,2'E)-3,3'-(5,5-Dioxo-5H-5λ6-dibenzo[b,d]thiene-2,8-di-
yl)di(prop-2-enal) (4b)
The title compound was prepared from aldehyde 3b (544 mg)
following the general procedure B. After filtration step, the
column chromatography was employed to separate mono
product. The product 4b was obtained as a yellowish solid (253
mg, 39 %). Rf = 0.20 (CH2Cl2/EtOAc 20:1); Td> 350 °C.
1H-NMR (500 MHz, 25 °C, d6-DMSO): δ = 7.19 (dd, J1 = 16 Hz,
J2 = 7.5 Hz, 2H, CH), 7.93 (d, J = 15.5 Hz, 2H, CH), 8.03 (d, J =
8 Hz, 2H, CHAR), 8.19 (d, J = 7.5 Hz, 2H, CHAR), 8.83 (s, 2H,
CHAR), 9.84 ppm (d, J = 7.5 Hz, 2H,CH=O). 13C-NMR (125
MHz, 25 °C, d6-DMSO): δ = 121.78; 123.09; 131.43; 131.52;
132.65; 138.55; 140.40; 150.60; 194.88 ppm. HR-FT-MALDI-
MS (DHB) m/z: calculated for C18H13O4S+ ([M+H]+): 325.05291;
found 325.05329.
4.15. DBT-chromophore (8a)
The title chromophore was prepared from aldehyde 4a
(146 mg) following the general procedure E. The product was
obtained as a bright orange solid (287 mg, 78 %). Rf = 0.80
(CH2Cl2/Hexane 3:1); Tm = 210 °C; Td> 260 °C. 1H-NMR
(500 MHz, 25 °C, CDCl3): δ = 0.94−0.99 (m, 12H, CH3),
1.35−1.45 (m, 8H, CH2), 1.60−1.68 (m, 8H, CH2), 3.94−3.97 (m,
8H, CH2), 7.56 (d, J = 15 Hz, 2H, CH), 7.83−7.88 (m, 4H,
2×CHAR), 8.22 (d, J = 12 Hz, 2H, CH), 8.37 (s, 2H, CHAR), 8.70
ppm (dd, J1 = 15.5 Hz, J2 = 12 Hz, 2H, CH). 13C-NMR
(125 MHz, 25 °C, CDCl3): δ = 14.00; 14.04; 20.39; 20.49; 30.36;
30.43; 41.73; 42.23; 114.88; 123.25; 123.73; 125.47; 127.26;
132.66; 135.38; 143.24; 151.12; 153.73; 157.14; 161.81;
162.24 ppm. HR-FT-MALDI-MS (DHB) m/z: calculated for
C42H49N4O6S+ ([M+H]+): 737.33226; found 737.33669.
4.11. 3,3'-(Dibenzo[b,d]thiene-2,8-diyl)di(prop-2-yn-1-ol) (5a)
The title compound was prepared from bromo derivative 2a
(1.026 g) following the general procedure C. The product was
obtained as a light ocher solid (465 mg, 53 %). Rf = 0.60
1
(CH2Cl2/EtOAc 1:1); Td > 200 °C. H-NMR (500 MHz, 25 °C,
d6-DMSO): δ = 4.41 (d, J = 6 Hz, 4H, CH2), 5.47 (t, J = 6 Hz,
2H, OH), 7.61 (dd, J1 = 8 Hz, J2 = 1 Hz, 2H, CHAR), 8.11 (d,
J = 8.5 Hz, 2H, CHAR), 8.61 ppm (d, J = 0.5 Hz, 2H, CHAR).
13C-NMR (125 MHz, 25 °C, d6-DMSO): δ = 49.54; 83.66; 90.06;
119.11; 123.45; 125.26; 130.17; 134.67; 139.08 ppm. HR-FT-
MALDI-MS (DHB) m/z: calculated for C18H12O2S+ ([M]+):
292.05525; found 292.05556.
4.16. DBTO-chromophore (8b)
The title chromophore was prepared from aldehyde 4b
(162 mg) following the general procedure E. The product was
obtained as a yellow solid (185 mg, 48 %). Rf = 0.95
(CH2Cl2/EtOAc 20:1); Tm = 247 °C; Td> 270 °C. 1H-NMR
(500 MHz, 25 °C, CDCl3): δ = 0.94−0.99 (m, 12H, CH3);
1.35−1.44 (m, 8H, CH2), 1.58−1.67 (m, 8H, CH2), 3.95−3.98 (m,
8H, CH2), 7.45 (d, J = 16 Hz, 2H, CH), 7.85−7.89 (m, 4H,
2×CHAR), 8.09 (s, 2H, CHAR), 8.19 (d, J = 12 Hz, 2H, CH),
8.74 ppm (dd, J1 = 16 Hz, J2 = 12 Hz, 2H, CH). 13C-NMR
(125 MHz, 25 °C, CDCl3): δ = 13.99; 14.03; 20.37; 20.47; 30.32;
30.39; 41.90; 42.41; 117.26; 121.84; 123.18; 128.59; 130.99;
132.07; 139.34; 141.25; 149.71; 150.89; 155.41; 161.53;
161.82 ppm. HR-FT-MALDI-MS (DHB) m/z: calculated for
C42H49N4O8S+ ([M+H]+): 769.32656; found 769.32741.
4.12. 2,8-Bis(3-hydroxyprop-1-yn-1-yl)-5H-5λ6-dibenzo[b,d]thio-
phene-5,5-dione) (5b)
The title compound was prepared from bromo derivative 2b
(1.122 mg) following the general procedure C. The product was
obtained as a light ocher solid (525 mg, 54 %). Rf = 0.40
1
(CH2Cl2/EtOAc 1:1); Td > 210 °C. H-NMR (500 MHz, 25 °C,
d6-DMSO): δ = 4.43 (d, J = 6 Hz, 4H, CH2), 5.57 (t, J = 6 Hz,
2H, OH), 7.73 (d, J = 8 Hz, 2H, CHAR), 8.06 (d, J = 8 Hz, 2H,
CHAR), 8.47 ppm (s, 2H, CHAR). 13C-NMR (125 MHz, 25 °C, d6-
DMSO): δ = 49.46; 82.27; 94.07; 122.47; 125.86; 128.69;
130.82; 133.92; 136.26 ppm. HR-FT-MALDI-MS (DHB) m/z:
calculated for C18H13O4S+ ([M+H]+): 325.05291; found
325.05329.
4.17. DBT-chromophore (9a)
The title chromophore was prepared from aldehyde 6a
(144 mg) following the general procedure E. The product was
obtained as a bright yellow solid (260 mg, 71 %). Rf = 0.80
1
(CH2Cl2/Hexane 3:1); Td> 160 °C. H-NMR (500 MHz, 25 °C,
4.13. 3,3'-(Dibenzo[b,d]thiene-2,8-diyl)di(prop-2-ynal)(6a)
CDCl3): δ = 0.94−0.99 (m, 12H, CH3); 1.36−1.44 (m, 8H, CH2),
1.61−1.69 (m, 8H, CH2), 3.94−4.00 (m, 8H, CH2), 7.80 (dd,
J1 = 8.5 Hz, J2 = 1.5 Hz, 2H, CHAR), 7.84 (s, 2H, CH), 7.91 (d,
J = 8 Hz, 2H, CHAR), 8.49 ppm (d, J = 1 Hz, 2H, CHAR). 13C-
The title compound was prepared from alcohol 5a (584 mg)
following the general procedure D. The product was obtained as
a light orange solid (253 mg, 44 %). Rf = 0.85 (CH2Cl2); Td> 215

9
NMR (125 MHz, 25 °C, CDCl3): δ = 13.97; 14.03; 20.36; 20.43;
Chem. 16 (1974) 181–288. doi:10.1016/b978-0-08-
025256-8.50013-9.
ACCEPTED MANUSCRIPT
30.30; 30.33; 41.90; 42.41; 90.62; 117.45; 118.68; 123.48;
125.67; 127.21; 132.11; 135.22; 136.25; 143.01; 150.82; 159.40;
161.23 ppm. HR-FT-MALDI-MS (DHB) m/z: calculated for
C42H45N4O6S+ ([M+H]+): 733.30543; found 733.30634.
[9]
Q. Hou, W. Yang, C. Liu, R. Yang, Y. Cao, J. Huang,
Y. Niu, Improvement of color purity in blue-emitting
polyfluorene
by
copolymerization
with
4.18. DBTO-chromophore (9b)
dibenzothiophene, J. Mater. Chem. 13 (2003)
1351−1355. doi:10.1039/b300202k.
The title chromophore was prepared from aldehyde 6b
(160 mg) following the general procedure E. The product was
obtained as a dark yellow solid (157 mg, 41 %). Rf = 0.95
[10]
T. Shan, P. Lu, X. Tang, X. He, Q. Bai, H. Ma,
Efficient Deep-Blue Electroluminescence Based on
Phenanthroimidazole-Dibenzothiophene Derivatives
with Different Oxidation States of the Sulfur Atom,
1
(CH2Cl2/EtOAc 20:1); Td> 160 °C. H-NMR (500 MHz, 25 °C,
CDCl3): δ = 0.94−0.98 (m, 12H, CH3); 1.34−1.43 (m, 8H, CH2),
1.59−1.67 (m, 8H, CH2), 3.94−3.97 (m, 8H, CH2), 7.76 (s, 2H,
CH), 7.84−7.89 (m, 4H, 2×CHAR), 8.07 ppm (s, 2H, CHAR).
13C-NMR (125 MHz, 25 °C, CDCl3): δ = 13.95; 14.00; 20.33;
20.39; 30.25; 30.27; 42.03; 42.54; 91.56; 111.85; 122.85; 126.06;
127.66; 128.06; 131.28; 134.62; 135.61; 138.97; 150.55; 159.07;
160.72 ppm. HR-FT-MALDI-MS (DHB) m/z: calculated for
C42H45N4O8S+ ([M+H]+): 765.29526; found 765.29637.
Chem.
-
An Asian J. 12 (2017) 552–560.
doi:10.1002/asia.201601626.
[11]
[12]
A. Liang, M. Luo, Y. Liu, H. Wang, Z. Wang, X.
Zheng, T. Cao, D. Liu, Y. Zhang, F. Huang, Novel
yellow phosphorescent iridium complexes with
dibenzothiophene-S,S-dioxide-based cyclometalated
ligand for white polymer light-emitting diodes, Dye.
Acknowledgments
Pigment.
159
(2018)
637–645.
For I. V. Kityk and J. Jedyrka the presented results are the part
of a project that has received funding from the European Union’s
Horizon 2020 research and innovation program under the
Marie Skłodowska-Curie grant agreement No. 778156.
Supported from resources for science in years 2018-2022 granted
for the realization of international co-financed project No.
W13/H2020/2018 (Dec. MNiSW 3871/H2020/2018/2) is
also acknowledged.
doi:10.1016/j.dyepig.2018.07.019.
K.C. Moss, K.N. Bourdakos, V. Bhalla, K.T.
Kamtekar, M.R. Bryce, M.A. Fox, H.L. Vaughan,
F.B. Dias, A.P. Monkman, Tuning the intramolecular
charge transfer emission from deep blue to green in
ambipolar systems based on dibenzothiophene
S,S-dioxide by manipulation of conjugation and
strength of the electron donor units, J. Org. Chem. 75
(2010) 6771–6781. doi:10.1021/jo100898a.
5. References and notes
[1]
M. E. Forrest, S. R. Thompson, Organic Electronics
and Optoelectronics, Chem. Rev. 107 (2007) 923–
1386.
[13]
[14]
S. Kumar, S. Patil, High Tg fluoranthene-based
electron transport materials for organic light-emitting
diodes, New J. Chem. 39 (2015) 6351–6357.
doi:10.1039/c5nj00750j.
[2]
[3]
E. A. Miller, R. D. Chandross, Materials for
Electronics, Chem. Rev. 110 (2010) 1–574.
Y.S. Kim, J.Y. Yoon, H.W. Lee, J. Kim, H.W. Lee,
S.E. Lee, Y.K. Kim, S.S. Yoon, Blue fluorescent
materials based on bis(10-phenylanthracen-9-yl)
derivatives containing heterocyclic moiety, Opt.
P. N. He, G. S. Tan, L. S. Zheng, Q. Prasad,
Multiphoton Absorbing Materials:ꢀ Molecular
Designs, Characterizations, and Applications, Chem.
Rev. 108 (2008) 1245–1330.doi: 10.1021/cr050054x.
Mater.
(Amst).
46
(2015)
247–253.
[4]
Y. Ohmori, Development of organic light emitting
diodes for electro optical integrated devices, Laser
doi:10.1016/j.optmat.2015.04.027.
[15]
[16]
[17]
[18]
W. Huang, M. Jiang, S. Qian, B. Li, X. Wang, P.
Yang, W. Jiang, X. Tao, Two-photon absorption of
Photonics
10.1002/lpor.200810059.
Rev.
4
(2010)
300–310.
doi:
new
multibranched
chromophore
with
[5]
[6]
F. Bureš, Fundamental aspects of property tuning in
push-pull molecules, RSC Adv. 4 (2014) 58826–
58851. doi:10.1039/c4ra11264d.
dibenzothiophene core, Chem. Phys. Lett. 424 (2006)
333–339. doi:10.1016/j.cplett.2006.04.099.
T.H. Huang, W.T. Whang, J.Y. Shen, J.T. Lin, H.
Zheng, Organic electroluminescent derivatives
containing dibenzothiophene and diarylamine
segments, J. Mater. Chem. 15 (2005) 3233–3240.
doi:10.1039/b507210g.
D. F. Perepichka, I. F. Perepichka, Handbook of
Thiophene Based Materials: Applications in Organic
Electronics and Photonics, John Wiley & Sons, Ltd,
2009. doi:10.1002/9780470745533.
[7]
[8]
J. Podlesný, O. Pytela, M. Klikar, V. Jelínková, I. V.
Kityk, K. Ozga, J. Jedryka, M. Rudysh, F. Bureš,
Small isomeric push–pull chromophores based on
thienothiophenes with tunable optical (non)linearities,
Org. Biomol. Chem. 17 (2019) 3623–3634.
doi:10.1039/C9OB00487D.
T.H. Huang, J.T. Lin, L.Y. Chen, Y.T. Lin, C.C. Wu,
Dipolar dibenzothiophene S,S-dioxide derivatives
containing diarylamine: Materials for single-layer
organic light-emitting devices, Adv. Mater. 18 (2006)
602–606. doi:10.1002/adma.200502078.
J.H. Kim, J.Y. Lee, Dibenzothiophene-dioxide
acceptor based thermally activated delayed
C. C. Ashby, J. Cook, Recent Advances in the
Chemistry of Dibenzothiophenes, Adv. Heterocycl.

10
Tetrahedron
ACCEPTED MANUSCRIPT
fluorescent emitters for color tunable organic light-
6672–6679. doi:10.1021/jo070607z.
emitting diodes, J. Ind. Eng. Chem. 50 (2017) 111–
114. doi:10.1016/j.jiec.2017.02.001.
[29]
[30]
[31]
[32]
C. Wang, S. Cai, X. Li, X. Hu, J. Su, Z. Zhang, J.
Han, Efficient organic dyes containing dibenzo
heterocycles as conjugated linker part for dye-
sensitized solar cells, Tetrahedron. 69 (2013) 1970–
1977. doi:10.1016/j.tet.2012.12.074.
[19]
[20]
S.H. Hsiao, L.C. Wu, Fluorescent and electrochromic
polymers from 2,8-di(carbazol-9-yl)dibenzothiophene
and its S,S-dioxide derivative, Dye. Pigment. 134
(2016) 51–63. doi:10.1016/j.dyepig.2016.06.043.
M. Klikar, I.V. Kityk, D. Kulwas, T. Mikysek, O.
Pytela, F. Bureš, Multipodal arrangement of push-pull
chromophores: a fundamental parameter affecting
their electronic and optical properties, New J. Chem.
41 (2017)1459−1472. doi:10.1039/c6nj02994a.
Z. Chen, J. Ye, C. Zheng, C.S. Lee, Y. Yuan, X. Ou,
X. Zhang, M. K. Fung, Carbazole/Sulfone Hybrid
D-π-A-Structured Bipolar Fluorophores for High-
Efficiency Blue-Violet Electroluminescence, Chem.
Mater.
25
(2013)
2630–
M. Klikar, F. Bureš, O. Pytela, T. Mikysek, Z.
Padělková, A. Barsella, K. Dorkenoo, S. Achelle,
N,N′-Dibutylbarbituric acid as an acceptor moiety in
push-pull chromophores, New J. Chem. 37 (2013)
4230−4240. doi:10.1039/c3nj00683b.
2637.doi:10.1021/cm400945h.
[21]
[22]
[23]
J.H. Kim, S.H. Han, J.Y. Lee, Dibenzothiophene
derived hosts with CN substituted carbazole for blue
thermally activated delayed fluorescent organic light-
emitting diodes, Synth. Met. 232 (2017) 152–158.
doi:10.1016/j.synthmet.2017.08.014.
M. Klikar, V. Jelínková, Z. Růžičková, T. Mikysek,
O. Pytela, M. Ludwig, F. Bureš, Malonic Acid
Derivatives on Duty as Electron-Withdrawing Units
in Push–Pull Molecules, European J. Org. Chem.
2017 (2017)2764−2779. doi:10.1002/ejoc.201700070.
J. Gao, L. Li, Q. Meng, R. Li, H. Jiang, H. Li, W. Hu,
Dibenzothiophene derivatives as new prototype
semiconductors for organic field-effect transistors, J.
Mater.
doi:10.1039/b616381e.
Chem.
17
(2007)
1421–1426.
[33]
[34]
J. Korang, W.R. Grither, R.D. McCulla,
Photodeoxygenation of dibenzothiophene S-oxide
derivatives in aqueous media, J. Am. Chem. Soc. 132
(2010) 4466–4476. doi:10.1021/ja100147b.
X.J. Feng, P.L. Wu, F. Bolze, H.W.C. Leung, K.F. Li,
N.K. Mak, D.W.J. Kwong, J.F. Nicoud, K.W. Cheah,
M.S. Wong, Cyanines as new fluorescent probes for
DNA detection and two-photon excited bioimaging,
M. Blanchard-Desce, V. Alain, P. V. Bedworth, S.R.
Marder, A. Fort, C. Runser, M. Barzoukas, S. Lebus,
R. Wortmann, Large quadratic hyperpolarizabilities
with donor-acceptor polyenes exhibiting optimum
bond length alternation: Correlation between structure
and hyperpolarizability, Chem. - A Eur. J. 3 (1997)
1091–1104. doi:10.1002/chem.19970030717.
Org.
Lett.
12
(2010)
2194–2197.
doi:10.1021/ol100474b.
[24]
[25]
[26]
S. Chi, L. Li, Y. Wu,
A
series of novel
dibenzothiophene-based
probes for cellular nucleus imaging, Sensors
Actuators, Chem. 231 (2016) 811–829.
two-photon
fluorescent
B
[35]
[36]
[37]
D.B. Dess, J.C. Martin, Readily Accessible 12-I-5
oxidant for the Conversion of Primary and Secondary
Alcohols to Aldehydes and Ketones, J. Org. Chem. 48
(1983) 4155–4156. doi:10.1021/jo00170a070.
doi:10.1016/j.snb.2016.03.006.
S. Chi, L. Li, Y. Wu, Novel mono-cationic fluorescent
probes based on different central π-conjugated bridges
for two-photon bioimaging of cellular nuclei, RSC
F. Texier-Boullet, A. Foucaud, Knoevenagel
condensation catalysed by aluminium oxide.,
Adv.
6
(2016)
69748–69757.
doi:10.1039/c6ra12193d.
Tetrahedron
Lett.
23
(1982)
4927–4928.
C.Y. Huang, J. Wang, Z.Y. Ding, K. Cui,
Luminescent properties, internal hydrogen bonds and
π-π Interactions of Cd(II), Zn(II), Co(II) complexes
based on 2,8-di(pyridin-4-yl)dibenzothiophene and
dicarboxylate ligands, J. Mol. Struct. 1086 (2015)
118–124. doi:10.1016/j.molstruc.2015.01.020.
doi:10.1016/S0040-4039(00)85749-4.
D. Cvejn, E. Michail, K. Seintis, M. Klikar, O. Pytela,
T. Mikysek, N. Almonasy, M. Ludwig, V. Giannetas,
M. Fakis, F. Bureš, Solvent and branching effect on
the two-photon absorption properties of push-pull
triphenylamine derivatives, RSC Adv. 6 (2016)
12819–12828. doi:10.1039/c5ra25170b.
[27]
[28]
Y.J. Kang, J.Y. Lee, High triplet energy electron
transport type exciton blocking materials for stable
blue phosphorescent organic light-emitting diodes,
Org. Electron. Physics, Mater. Appl. 32 (2016) 109–
114. doi:10.1016/j.orgel.2016.02.025.
[38]
[39]
A. Isse, A. A.; Gennaro, Absolute Potential of the
Standard Hydrogen Electrode and the Problem of
Interconversion of Potentials in Different Solvents, J.
Phys. Chem. B. 114 (2010) 7894–7899.
K. L. Pik, F.L. King, S.W. Man, W.C. Kok, Synthesis
and structure-linear and structure-nonlinear optical
properties
J.L. Sawyer, D. T. Sobkowiak, A. Roberts,
Electrochemistry for Chemists, 2nd edition, J. Wiley
and Sons Inc., 1995. ISBN: 978-0-471-59468-0.
of
multi-dipolar
zigzag
oligoaryleneethynylenes, J. Org. Chem. 72 (2007)

11
[40]
[41]
T. Kolev, I. V. Kityk, J. Ebothe, B. Sahraoui, Intrinsic
Heyd, E. N. Brothers, K. N. Kudin, V. N.
ACCEPTED MANUSCRIPT
hyperpolarizability
dimethyl-1-[2-(4-hydroxyphenyl)ethenyl]-cyclohexe-
ne nanocrystallites incorporated into the
of
3-dicyanomethylene-5,5-
Staroverov, T. A. Keith, R. Kobayashi, J. Normand,
K. Raghavachari, A. P. Rendell, J. C. Burant, S. S.
Iyengar, J. Tomasi, M. Cossi, J. M. Millam, M. Klene,
C. Adamo, R. Cammi, J. W. Ochterski, R. L. Martin,
K. Morokuma, O. Farkas, J. B. Foresman, D. J. Fox,
Gaussian 16, Revision A.03, (2016).
photopolymer matrices, Chem. Phys. Lett. 443 (2007)
309–312. doi:10.1016/j.cplett.2007.06.051.
E. Cariati, C. Botta, S.G. Danelli, A. Forni, A.
Giaretta, U. Giovanella, E. Lucenti, D. Marinotto, S.
Righetto, R. Ugo, Solid state and solution fine tuning
of the linear and nonlinear optical properties of (2-
[48]
[49]
O. Pytela, OPChem, http://bures.upce.cz/OPgm.
O. Wennerstrom, V. Boekelheide, R.B. DuVernet, T.
Otsubo, J. Lawson, Bridged [18]annulenes. A study of
the synthesis and properties of 12c,12d,12e,12f-
tetrahydrobenzo[g,h,i]perylene and its analogs, J. Am.
pyrene-1-yl-vinyl)pyridine
by
protonation-
deprotonation reactions, Chem. Commun. 50 (2014)
14225–14228. doi:10.1039/c4cc05891g.
Chem.
Soc.
100
(1978)
2457–2464.
[42]
K. Pielak, C. Tonnelé, L. Sanguinet, E. Cariati, S.
Righetto, L. Muccioli, F. Castet, B. Champagne,
Dynamical Behavior and Second Harmonic
Generation Responses in Acido-Triggered Molecular
Switches, J. Phys. Chem. C. 122 (2018) 26160–
26168. doi:10.1021/acs.jpcc.8b08697.
doi:10.1021/ja00476a032.
Supplementary Material
Supplementary data to this article can be found online at…
[43]
[44]
[45]
A. Majchrowski, I. V. Kityk, J. Ebothé, Influence of
YAB: Cr3+ nanocrystallite sizes on two-photon
absorption of YAB:Cr3+, Phys. Status Solidi Basic
Res.
241
(2004)
3047–3055.
doi:10.1002/pssb.200402071.
Y. Qian, M. Cai, S. Wang, Y. Yi, Z. Shuai, G. Yang,
Synthesis and third-order optical nonlinearities of
nickel complexes of 8-hydroxyquinoline derivatives,
Opt.
Commun.
283
(2010)
2228–2233.
doi:10.1016/j.optcom.2010.01.026.
K. Ozga, A. Wojciechowski, M. Nabialek, M. Szota,
M. Dospial, V. Kapustianyk, V. Rudyk, A.O.
Fedorchuk, Specific features of photoinduced
absorption and second harmonic generation of ferroic
organic nanocomposites [C3H7NH3]2MnCl4, Opt.
Quantum
Electron.
47
(2015)
743–753.
doi:10.1007/s11082-014-9949-4.
[46]
P. Szlachcic, A.A. Fedorchuk, A. Danel, B. Jarosz,
A.M. El Naggar, A.A. Albassam, A. Wojciechowski,
E. Gondek, T. Uchacz, K. Stadnicka, G.
Lakshminarayana, I. V. Kityk, Optically operated
second order optical effects in some substituted 4-(5-
nitro-1,3-benzoxazol-2-yl)aniline chromophores, Dye.
Pigment.
141
(2017)
333–341.
doi:10.1016/j.dyepig.2017.02.009.
[47]
M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E.
Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani,
V. Barone, G. A. Petersson, H. Nakatsuji, X. Li, M.
Caricato, A. V. Marenich, J. Bloino, B. G. Janesko, R.
Gomperts, B. Mennucci, H. P. Hratchian, J. V. Ortiz,
A. F. Izmaylov, J. L. Sonnenberg, D. Williams-
Young, F. Ding, F. Lipparini, F. Egidi, J. Goings, B.
Peng, A. Petrone, T. Henderson, D. Ranasinghe, V. G.
Zakrzewski, J. Gao, N. Rega, G. Zheng, W. Liang, M.
Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H.
Nakai, T. Vreven, K. Throssell, J. A. Montgomery,
Jr., J. E. Peralta, F. Ogliaro, M. J. Bearpark, J. J.

ACCEPTED MANUSCRIPT
Highlights
• New series of dibenzothiophene-based chromophores with two peripheral barbituric
acceptors possessing extraordinary push-pull or pull-pull structural arrangement.
• Fundamental thermal and optoelectronic properties supported by nonlinear optical
responses and DFT calculations.
• Thorough structure–property relationships/ICT assessment and correlation of the
experimental and theoretical data.